Patent Document 1 discloses a conventional swash plate type variable displacement compressor (hereinafter referred to as a compressor). This compressor includes a front housing member, a cylinder block, and a rear housing member, which form a housing. The front housing member and the rear housing member each include a suction chamber and a discharge chamber. The rear housing member also includes a control pressure chamber.
The cylinder block includes a swash plate chamber, a plurality of cylinder bores, and a main shaft through hole. Each cylinder bore includes a first cylinder bore formed in the rear part of the cylinder block and a second cylinder bore formed in the front part of the cylinder block. The main shaft through hole is formed in the rear part of the cylinder block and communicates with the swash plate chamber and the control pressure chamber.
The drive shaft is inserted in the housing and is rotationally supported in the cylinder block. The swash plate chamber accommodates a swash plate, which is rotatable through rotation of the drive shaft. A link mechanism, which allows change of the inclination angle of the swash plate, is arranged between the drive shaft and the swash plate. The inclination angle is defined as the angle of the swash plate with respect to a direction perpendicular to the rotation axis of the drive shaft.
Each cylinder bore reciprocally accommodates a piston. More specifically, each piston includes a first piston head that reciprocates in the first cylinder bore and a second piston head that reciprocates in the second cylinder bore. Thus, the first cylinder bore and the first piston head form a first compression chamber, and the second cylinder bore and the second piston head form a second compression chamber. A conversion mechanism reciprocates each of the pistons in the associated one of the cylinder bores by the stroke corresponding to the inclination angle through rotation of the swash plate. An actuator is capable of changing the inclination angle and controlled by a control mechanism.
The actuator is arranged in the swash plate chamber closer to the first cylinder bores relative to the swash plate. The actuator includes a non-rotational movable body, a movable body, a thrust bearing, and the control pressure chamber. The non-rotational movable body is arranged in the main shaft through hole not to rotate integrally with the drive shaft and covers the rear end of the drive shaft. The inner circumferential surface of the non-rotational movable body rotationally and slidably supports the rear end of the drive shaft. The outer circumferential surface of the non-rotational movable body slides in the main shaft through hole along the rotation axis so that the non-rotational movable body moves in the main shaft through hole in the front-rear direction. However, the non-rotational movable body does not slide about the rotation axis of the non-rotational movable body. The movable body is coupled to the swash plate and is movable along the rotation axis. The thrust bearing is located between the non-rotational movable body and the movable body.
Since the non-rotational movable body is arranged in the main shaft through hole, the main shaft through hole is partitioned into a rear end portion that communicates with the control pressure chamber and a front end portion that does not communicate with the control pressure chamber. The rear end portion of the main shaft through hole communicates with the control pressure chamber and functions as part of the control pressure chamber. The rear end portion has a pressing spring, which urges the non-rotational movable body forward.
The control mechanism includes a control passage and a control valve provided in the control passage. The control passage connects the control pressure chamber to the discharge chamber. The control valve adjusts the opening degree of the control passage to change the pressure in the control pressure chamber so that the non-rotational movable body and the movable body are movable along the rotation axis.
The link mechanism has a movable body and a lug arm fixed to the drive shaft. A rear end portion of the lug arm has an elongated hole, which extends in a direction perpendicular to the rotation axis of the drive shaft from the radially outer side toward the rotation axis. A pin is received in the elongated hole and supports the swash plate at a position forward to the swash plate such that the swash plate is allowed to pivot about a first pivot axis. A front end portion of the movable body also has an elongated hole, which extends in the direction perpendicular to the rotation axis of the drive shaft from the radially outer side toward the rotation axis. A pin is passed through the elongated hole and supports the swash plate at the rear end of the swash plate such that the swash plate is allowed to pivot about a second pivot axis, which is parallel to the first pivot axis.
The control valve of this compressor is capable of controlling the pressure in the control pressure chamber by the pressure of discharge refrigerant in the discharge chamber through adjustment of the opening degree of the control passage. Thus, the actuator of this compressor changes the inclination angle of the swash plate to allow change in the displacement per rotation of the drive shaft.